again, president obama is looking to monitor this situation into the evening. lawrence? >> thank you. joining me now with the latest on that investigation, nbc news justice correspondent, pete williams. >> lawrence, good evening. investigators know this attack involved two bombs. what they don't know is whether there were other explosives involved. at least five other packages found on the street were deemed to be suspicious and destroyed by boston police and bomb squad techs. there were many packages to check. people dropped what they were carrying and ran away. we have heard conflicting accounts about whether there were unexploded bombs. some say two other packages were found that contained forms of explosiv explosives, others say there were just the two bombs. that remains unclear. several officials say the bombs that did go off included shrapnel that multiplied the injuries, b.b.s and ball bearingings. they are looking at surveillance video to see if they can see anyone placing packages at the points where the bombs went off. they described them with crude and less e